U.S. patent number 4,214,062 [Application Number 05/875,014] was granted by the patent office on 1980-07-22 for polycarbonate films of low flammability and improved stress crack resistance.
This patent grant is currently assigned to Bayer Aktiengesellschaft. Invention is credited to Rudolf Binsack, Eckart Reese, Joachim Wank.
United States Patent |
4,214,062 |
Binsack , et al. |
July 22, 1980 |
Polycarbonate films of low flammability and improved stress crack
resistance
Abstract
The present invention relates to polycarbonate films, and in
particular extruded films and cast films, but preferably extruded
films, which are characterized in that they contain about 0.01% to
2% by weight of a NH.sub.4 salt, alkali metal salt or alkaline
earth metal salt of a perhalogenoalkanesulphonic acid, preferably a
perfluoroalkanesulphonic acid.
Inventors: |
Binsack; Rudolf (Krefeld,
DE), Wank; Joachim (Dormagen, DE), Reese;
Eckart (Dormagen, DE) |
Assignee: |
Bayer Aktiengesellschaft
(Leverkusen, DE)
|
Family
ID: |
6001114 |
Appl.
No.: |
05/875,014 |
Filed: |
February 3, 1978 |
Foreign Application Priority Data
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Feb 14, 1977 [DE] |
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2706126 |
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Current U.S.
Class: |
525/470; 264/211;
524/165; 525/462; 528/196 |
Current CPC
Class: |
C08K
5/42 (20130101); C08K 5/42 (20130101); C08L
69/00 (20130101) |
Current International
Class: |
C08K
5/00 (20060101); C08K 5/42 (20060101); C08K
005/42 () |
Field of
Search: |
;260/45.7SF,47XA,45.9R
;525/3,462,470 ;528/196 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2149311 |
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Apr 1973 |
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DE |
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1370744 |
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Oct 1974 |
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GB |
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Primary Examiner: Schain; Howard E.
Assistant Examiner: White; R. A.
Attorney, Agent or Firm: Harsh; Gene Pope; Lawrence S.
Claims
What is claimed is:
1. Polycarbonate films, characterized in that they contain about
0.01% by weight to 2% by weight of a NH.sub.4 salt, alkali metal
salt or alkaline earth metal salt of a perhalogenoalkanesulphonic
acid.
2. Polycarbonate films according to claim 1, characterized in that
they contain between about 0.01% by weight and 2% by weight of a
NH.sub.4 salt, alkali metal salt or alkaline earth metal salt of a
perfluoroalkanesulphonic acid.
3. Polycarbonate extruded films according to claim 1.
4. Polycarbonate films according to claim 1, characterized in that
they contain NH.sub.4 salts, alkali metal salts or alkaline earth
metal salts of perhalogenosulphonic acids of the formula I
wherein R represents C.sub.n Hal.sub.2n+1
in which
Hal is F or Cl and
n is 1 to 8, and
wherein Me is NH.sub.4, an alkali metal or an alkaline earth
metal.
5. Polycarbonate films according to claim 4, characterized in that
Me is potassium.
6. Polycarbonate films according to claim 1, characterized in that
the films additionally contain up to about 10% by weight of
low-molecular weight, halogen-containing aromatic polycarbonates
having average molecular weights Mn of about 4,000 to 20,000.
7. Polycarbonate films according to claim 6, characterized in that
the low-molecular weight, halogen-containing polycarbonate used is
one based on tetrabromobisphenol A.
8. Polycarbonate films according to claim 1, characterized in that
the polycarbonates used are high molecular weight, aromatic
copolycarbonates of about 99-90 mol % of bisphenol A and about 1-10
mol % of 1,1-bis-(4-hydroxyphenyl)-cyclohexane having average
molecular weights M.sub.w of about 30,000 to 120,000.
9. Polycarbonate films according to claim 8, characterized in that
the high molecular weight polycarbonates are branched with up to
about 0.5 mol %, relative to bisphenol A, of branching components
with at least three branching positions.
10. Polycarbonate films according to claim 1, characterized in that
mixtures of high-molecular weight polycarbonates having weight
average molecular weights, M.sub.w, of from about 25,000 to 80,000
are used.
11. A polycarbonate film consisting essentially of an aromatic
polycarbonate having a weight-average molecular weight, M.sub.w, of
between about 25,000 and 200,000 and about 0.1 to 2% by weight of a
perhalogenoalkanesulphonic acid salt selected from the group
consisting of a NH.sub.4 salt, an alkali metal salt and an alkaline
earth metal salt.
12. The polycarbonate film of claim 11 wherein the
perhalogenoalkanesulphonic acid salt is of the formula
wherein R represents C.sub.n Hal.sub.2n+1
wherein
Hal is F or Cl and
n is 1 to 8, and
Me is NH.sub.4, an alkali metal or an alkaline earth metal.
13. The polycarbonate film of claim 12 wherein the
perhalogenoalkanesulphonic acid salt is a perfluoroalkanesulphonic
acid salt.
14. A polycarbonate film consisting essentially of an aromatic
polycarbonate having a weight-average molecular weight, M.sub.w, of
between about 25,000 and 200,000, up to about 10% by weight of a
low-molecular weight, halogen-containing aromatic polycarbonate
having a number-average molecular weight, Mn, of about 4,000 to
20,000 and about 0.1 to 2% by weight of a
perhalogenoalkanesulphonic acid salt selected from the group
consisting of a NH.sub.4 salt, an alkali metal salt and an alkaline
earth metal salt.
15. A glass fiber-free polycarbonate film comprising an aromatic
polycarbonate having a weight-average molecular weight, M.sub.w, of
between about 25,000 and 200,000 and about 0.1 to 2% by weight of
perhalogenoalkanesulphonic acid salt selected from the group
consisting of a NH.sub.4 salt, an alkali metal salt and an alkaline
earth metal salt.
16. A process for improving the stress crack resistance of a
polycarbonate film comprising incorporating from about 0.01 to 2%
by weight of perhalogenoalkanesulphonic acid salt selected from the
group consisting of an NH.sub.4 salt, an alkali metal salt and an
alkaline earth metal salt into said polycarbonate film.
17. The process of claim 16 wherein the perhalogenoalkanesulphonic
acid salt is of the formula
wherein R represents C.sub.n Hal.sub.2n+1
wherein
Hal is F or Cl, and,
n is 1 to 8 and,
wherein Me is NH.sub.4, an alkali metal or an alkaline earth
metal.
18. A polycarbonate film consisting of an aromatic polycarbonate
having a weight average molecular weight, M.sub.w, of between about
25,000 and 200,000 and about 0.1 to 2% by weight of a
perhalogenoalkanesulphonic acid salt selected from the group
consisting of an NH.sub.4 salt, an alkali metal salt and an
alkaline earth metal salt.
Description
BACKGROUND OF THE INVENTION
Polycarbonate cast films of low flammability which consist of 90 to
70% by weight of a high-molecular polycarbonate based on bisphenol
A and 10 to 30% by weight of a low-molecular polycarbonate based on
halogeno bisphenols are known according to DT-OS (German Published
Specification) No. 2,345,533 (Le A 15318)resp. British Pat. No.
1458603. The high molecular polycarbonates based on bisphenol A
which have Mw, between about 70,000 and 120,000 are particularly
suitable in this situation.
It is known to render thermoplastic aromatic polycarbonates more
flame-repellent by adding halogenoalkanesulphonates. (See DT-OS
(German Published Specification) No. 1,930,257 (Le A 12 278), DT-OS
(German Published Specification) No. 2,253,072 (Le A 14723), U.S.
Pat. No. 3,775,367, DT-OS (German Published Specification) No.
2,460,944 and DT-OS (German Published Specification) No. 2,460,787
respectively U.S. Pat. No. 3,931,100).
It is also known to add ammonium salts of perfluoroalkanesulphonic
acids to thermoplastic aromatic polycarbonates, as mold release
agents for the manufacture of polycarbonate injection-molded
articles. (See DT-OS (German Published Specification) No. 2,506,726
(Le A 16 235) and U.S. Pat. No. 4,041,003. However, the use of
thermoplastic aromatic polycarbonates containing
halogenoalkanesulphonates for the manufacture of films, in
particular of extruded films, is not known.
SUMMARY OF THE INVENTION
The present invention relates to polycarbonate films, and in
particular extruded films and cast films, but preferably extruded
films, which are characterized in that they contain about 0.01 to
2% by weight, most preferably about 0.01 to 1% by weight, of a
NH.sub.4 salt, alkali metal salt or alkaline earth metal salt of a
perhalogenoalkanesulphonic acid, preferably a
perfluoroalkanesulphonic acid.
DETAILED DESCRIPTION OF THE INVENTION
The polycarbonate films according to the invention possess a
combination of good properties, such as fire-retardancy, stress
crack resistance, safety from electrolytic contact corrosion and,
in the case of extruded films, freedom from solvent.
The polycarbonate films according to the invention can, thus, be
preferably employed with great success as electrical insulating
films, which must be particularly resistant to stress cracking and
to electrolytic contact corrosion.
Films of polycarbonates containing alkali metal sulphonate (DT-OS
(German Published Specification) No. 2,149,311), of polycarbonates
containing soluble alkali metal salts (U.S. Pat. No. 3,836,490) and
of polycarbonates containing glass fibers and alkali metal salts of
perfluoroalkanesulphonic acid (DT-OS (German Published
Specification) No. 2,148,598 and U.S. Pat Nos. 3,845,007; 3,876,580
and 3,875,107) are now indeed known, but it was surprising that the
content according to the invention of perhalogenoalkanesulphonates,
in particular of perfluoroalkanesulphonates, in polycarbonate
films, besides reducing the flammability does not increase the
electrolytic conductivity and thus causes no contact corrosion when
the films are employed as electrical insulating films. It was
particularly surprising that the stress crack resistance is
improved in polycarbonate films by the addition, according to the
invention, of perhalogenosulphonates.
NH.sub.4, alkali metal and alkaline earth metal salts, which are
suitable according to the invention, of perhalogenosulphonic acids
are, in particular, those of the formula I
wherein R represents C.sub.n Hal.sub.2n+1
in which
Hal is F or Cl, preferably F and
n is 1 to 8, and
Me represents NH.sub.4, an alkali metal, such as, for example,
lithium, sodium or potassium, or an alkaline earth metal, such as,
for example, magnesium, calcium, strontium or barium.
Me is preferably potassium.
Suitable perhalogenosulphonates are the NH.sub.4 or alkali metal or
alkaline earth metal salts of the following
perhalogenoalkanesulphonic acids: perfluoromethanesulphonic acid,
perfluoroethanesulphonic acid, perfluoropropanesulphonic acid,
perfluorobutanesulphonic acid, perfluoromethylbutanesulphonic acid,
perfluorohexanesulphonic acid, perfluoroheptanesulphonic acid and
perfluorooctanesulphonic acid, and the corresponding
chloroalkanesulphonic acids.
The potassium salts of these perhalogenoalkanesulphonic acids are
particularly preferred.
The polycarbonate films according to the invention should
preferably have thicknesses between about 0.1 mm and 1 mm, most
preferably thicknesses between about 0.05 and 0.8 mm.
The additions, according to the invention, of
perhalogenoalkanesulphonates have the effect that
(a) the Oxygen Index (according to ASTM D 2863-74 and measured with
a film thickness of about 0.1 mm) is .gtoreq.25%,
(b) the flammability level (measured by the small burner test in
accordance with DIN 53,438) is K 1 and F 1,
(c) the flammability level (according to Test Instruction 94 of
Underwriters Laboratories in the supplement of 24.7.1974) is VTF-O,
in each case measured on films about 0.1 mm thick, and
(d) the electrolytic corrosion (according to DIN 53,489) is A
1.
Thermoplastic aromatic polycarbonates suitable for the preparation
of the polycarbonate films according to the invention may have
weight-average molecular weights, Mw, between about 25,000 and
200,000, preferably between about 30,000 and 120,000 and in
particular between about 30,000 and 80,000. Mw was determined by
measuring .eta..sub.rel in CH.sub.2 Cl.sub.2 at 20.degree. C. and a
concentration of about 0.5% by weight.
Thermoplastic aromatic polycarbonates which are suitable according
to the invention are, in particular, the homopolycarbonates of
2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A) and the
copolycarbonates of bisphenol A and up to about 10 mol %, relative
to mols of bisphenol A, of other diphenols and/or up to about 0.5
mol %, relative to mols of the total diphenols used, of branching
components possessing at least three branching positions, for
example, trisphenols or tetraphenols.
Suitable other diphenols which are suitable are
bis-(hydroxyaryl)-C.sub.1 -C.sub.8 -alkanes other than bisphenol A
and, in particular, bis-(hydroxyaryl)-C.sub.5 -C.sub.6
-cycloalkanes.
Suitable other diphenols are, for example,
bis-(4-hydroxyphenyl)-methane (bisphenol F),
2,4-bis-(hydroxyphenyl)-2-methylbutane,
2,2-bis-(3-methyl-4-hydroxyphenyl)-propane,
bis-(3,5-dimethyl-4-hydroxyphenyl)-methane,
2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane,
2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane,
1,1-bis-(4-hydroxyphenyl)-cyclohexane and
1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane.
Suitable branching components are, for example, phloroglucinol,
1,3,5-tris-(4-hydroxyphenyl)-benzene and
1,1,1-tris-(4-hydroxyphenyl)-ethane,
3,3-bis-(4-hydroxyphenyl)-2-oxo-2,3-dihydroindole
(isatin-bisphenol),
3,3-bis-(4-hydroxy-3-methylphenyl)-2-oxo-2,3-dihydroindole
(isatin-bis-o-cresol), 2,2-bis-[4
,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane,
tetra-(4-hydroxyphenyl)-methane,
tetra-(4-(4-hydroxyphenyl-isopropyl)-phenoxy)-methane and 1,4-
bis-((4',4"-dihydroxy-triphenyl)-methyl)-benzene. Branching
components which are preferably suitable are isatin-bisphenol,
isatin-bis-o-cresol and
1,4-bis-((4',4"-dihydroxy-triphenyl)-methyl)-benzene.
Suitable polycarbonates which are preferred according to the
invention are the copolycarbonates consisting of about 99-90 mol %
of 2,2-bis-(4-hydroxyphenyl)-propane and about 1 to 10 mol % of
1,1-bis-(4-hydroxyphenyl)-cyclohexane.
Suitable branched polycarbonates are, in particular, those of DT-OS
(German Published Specification) No. 2,254,917 (LeA 14,719), of
DT-OS (German Published Specification) No. 2,500,092 (LeA 16,142),
of DT-OS (German Published Specification) No. 2,113,347 (LeA
13,638) and of DT-OS (German Published Specification) No. 2,254,918
(LeA 14,711), and of U.S. Pat. Nos. 3,931,108; 3,799,953; 4,001,183
and 3,897,392, preferably those of DT-OS (German Published
Specification) No. 2,500,092 (LeA 16,142) and of DT-OS (German
Published Specification No. 2,113,347 (LeA 13,638) and of U.S. Pat.
Nos. 3,799,953 and 4,001,183.
The polycarbonates are prepared by processes which are known in the
art, for example, according to U.S. Pat. Nos. 3,028,365 and
3,275,601, incorporated herein by reference, and branched
polycarbonates are prepared by processes described according to
U.S. Pat. Nos. 3,544,514 or U.S. Pat. No. Re. 27,682, incorporated
herein by reference, i.e., for example, by the interfacial
process.
The polycarbonates can be used either alone or as a mixture with
other polycarbonates. Preferred mixtures are those of
polycarbonates in the molecular weight range (weight-average) from
about 25,000 to 35,000 with polycarbonates in the molecular weight
range (weight-average) from about 60,000 to 80,000 or with branched
polycarbonates in the molecular weight range (weight-average) from
about 40,000 to 60,000.
In addition to the sulphonates which are suitable according to the
invention, other, known compounds which reduce the flammability can
also be added to the polycarbonate films according to the invention
in amounts of up to about 10% by weight, relative to the total
weight of the polycarbonate film.
Halogen-containing, low-molecular aromatic polycarbonates with
average molecular weights, Mn (number-average), of about 4,000 to
20,000, preferably about 8,000 to 12,000, are preferably suitable
for this purpose. Such low-molecular polycarbonates are preferably
prepared from 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane,
2,2-bis-(3-bromo-4-hydroxyphenyl)-propane,
bis-(3,5-dibromo-4-hydroxyphenyl)-methane,
bis-(3-bromo-4-hydroxyphenyl)-methane,
2,4-bis-(3,5-dibromo-4-hydroxyphenyl)-2-methylbutane,
2,4-bis-(3-bromo-4-hydroxyphenyl)-2-methyl-butane, 1,1-
bis-(3,5-dibromo-4-hydroxyphenyl)-cyclohexane or
1,1-bis-(3-bromo-4-hydroxyphenyl)-cyclohexane. Phenol,
tert.-butylphenol, p-bromophenol and 2,4,6-tribromophenol are used
as chain-stoppers. Further details in this connection are described
in DT-OS (German Published Specification) No. 2,354,533 and in
DT-OS (German Published Specification) No. 2,243,226.
The films are manufactured either in the form of cast films by
known techniques, for example, by dissolving the polycarbonate and
the metal salts of the perhalogenoalkanesulphonic acids together in
a suitable solvent, such as methylene chloride or
1,2-dichloroethane, and, if appropriate, adding monohydric or
polyhydric alcohols, to give about 5 to 20% strength solutions
which are cast in belt or drum casting machines, or by the
extrusion of mixtures of the polycarbonate and the metal
sulphonates in the usual three-zone single flight screws or
twin-screw extruders according to the state of the art, it being
possible for the shaping into films to be carried out both via slit
dies to give flat films and via film blow-heads to give blown
films.
The low flammability of the films was determined by the following
methods:
1. Small Burner Test According to DIN 53,438
In this test, strip-shaped test pieces having the dimensions
190.times.90 mm.times.0.1 mm (edge-flaming) or 230.times.90
mm.times.0.1 mm (surface-flaming) are clamped vertically in a frame
and flamed with a propane gas flame 20 mm in length for 15 seconds.
In the case of edge-flaming, the tip of the flame just touches the
lower, exposed edge of the sample; in the case of surface-flaming,
the tip of the flame touches the surface of the sample 40 mm above
the lower edge of the sample. It is determined whether, and in what
time, calculated from the start of flaming, the tip of the flame of
the burning film reaches a marking located 150 mm above the point
at which the flame is applied.
Grading into the classes K 1, K 2 and K 3 and F 1, F 2 and F 3 is
carried out according to the following scheme:
______________________________________ Edge- Surface- flaming
Flaming ______________________________________ The flame does not
reach K 1 F 1 the measuring mark The tip of the flame reaches K 2 F
2 the measuring mark in 20 or more seconds The tip of the flame
reaches K 3 F 3 the measuring mark in less than 20 seconds
______________________________________
2. Determinatin of the Oxygen Index According to ASTM D 2863-74
The Oxygen Index is defined as the minimum volume concentration of
oxygen in a mixture of oxygen and nitrogen at which a test piece of
defined dimensions still just burns down candle-like from top to
bottom. Film strips having the dimensions 140.times.52.times.0.01
mm are clamped into a U-shaped container with the longitudinal axis
vertical and are ignited at the upper end with a gas flame. The
Oxygen Index is that volume concentration of oxygen at which the
film just burns down over a distance of 100 mm.
3. Test According to Test Instruction 94 of Underwriter's
Laboratories (UL)
UL 94 has hitherto contained no data for testing films. A revised
proposal for film testing as a supplement to UL 94 was published on
24.7.1974 by the body responsible for revising UL 94. According to
this proposal, 5 film strips having the dimensions
203.times.47.times.0.1 mm are each wound around a mandrel having a
diameter of 9.5 mm to give a roll of film 203 mm long. The rolls of
film are hung vertically and ignited twice on the underside with a
Bunsen burner flame, for 3 seconds each time. The length of the
samples subsequently burn, and whether cottonwool below the sample
is ignited by material which falls off are determined.
The following levels are proposed for the classification:
94 VTF-0
Films which neither produce burning drips nor burn up to a
measuring mark located 127 mm above the flamed end of the roll of
film. The maximum after-burning time may not exceed 10 seconds and
the sum of the after-burning times of 10 flamings may not exceed 50
seconds.
94 VTF-1
Requirements as for level 94 VTF-0, but the maximum after-burning
time may not exceed 30 seconds and the sum of the after-burning
times of 10 flamings is a maximum of 250 seconds.
94 VTF-2
Requirements as for level 94 VTF-1, but produces burning drips.
If a sample burns for longer than 20 seconds, it is not possible to
grade it in one of the three classes.
The determination of the electrolytic corrosion action is carried
out according to DIN 53,489, the classification A 1 having the
meaning "no electrolytic corrosion" both for the cathode and for
the anode; the classification AN 2 having the meaning degree of
corrosion 2 for the anode and degree of corrosion 6 for the
cathode.
In order to measure the stress cracking, film strips 15 mm wide and
0.1 mm thick are wound spirally around a glass rod of 8 mm diameter
and then stored in toluene/n-propanol mixtures for 10 seconds.
After drying, the film strips are subjected to the tensile test
according to DIN 53,455.
The polycarbonate films according to the invention are
distinguished by a greatly reduced flammability, a low
susceptibility to stress cracking, a low or non-measurable
electrolytic corrosion and a high electrical resistance and, in
addition to their stability compared with unsaturated polyester
cast resins, they exhibit the good mechanical, dielectric and heat
properties which are typical of polycarbonate films.
EXAMPLES
The examples which follow illustrate the invention. The
flammability, Oxygen Index and stress cracking tests were conducted
on films 0.1 mm in thickness.
EXAMPLE 1
99.5 parts of a bisphenol A polycarbonate, branched with 0.4 mol %
of isatin-bisphenol, which was prepared according to DT-OS (German
Published Specification) No. 2,500,092 and which has a relative
viscosity of 1.42 (measured in a 0.5% strength solution in
methylene chloride) and 0.5 parts of potassium
perfluorobutanesulphonate were melted in a twin-screw extruder
(type ZSK 53 from Werner and Pfleiderer) at 320.degree. C. and
homogenized. The extruded strand was cooled and, after being
granulated, was melted in a single-screw extruder (type S 45 from
Reifenhauser) at 280.degree. C. and shaped into a film via a 400 mm
wide slit die, the extrudate being drawn over a pair of cooling
rollers, heated to 90.degree. C., at such a rate that a film with a
thickness of 0.1 mm resulted.
EXAMPLE 2
Analogously to Example 1, a film was manufactured from the
bisphenol A polycarbonate, branched with the isatin-bisphenol, of
Example 1, 0.2% by weight of potassium perfluorobutanesulphonate
and 4% by weight of tetrabromobisphenol A polycarbonate (Mn about
8,000).
EXAMPLE 3
Analogously to Example 1, a film was manufactured from the
bisphenol A polycarbonate, branched with the isatin-bisphenol of
Example 1 and 0.5% by weight of potassium
perfluoromethanesulphonate.
EXAMPLE 4
Analogously to Example 1, a film was manufactured from the
bisphenol A polycarbonate, branched with isatin-bisphenol of
Example 1, and 0.6% by weight of potassium
perfluorooctanesulphonate.
COMPARISON EXAMPLE A to EXAMPLES 1-4
The bisphenol A polycarbonate, branched with the isatin-bisphenol
from Example 1 was extruded to give films 0.1 mm thick, by the
process described in Example 1 (a) without the addition and (b)
after the addition of 0.5% by weight of potassium acetate.
EXAMPLE 5
99.5 parts of a commercially available polycarbonate of bisphenol
A, having a relative viscosity of 1.32, and 0.5 part of potassium
perfluorobutanesulphonate were extruded to give films 0.1 mm thick
by the process described in Example 1.
COMPARISON EXAMPLE B to EXAMPLE 5
The polycarbonate from Example 5 was extruded to give films 0.1 mm
thick by the process described in Example 1 (a) without the
addition and (b) after the addition of 0.5% by weight of potassium
sulphate.
EXAMPLE 6 (COMPARISON EXAMPLE)
Analogously to Example 1, a film was manufactured from the
bisphenol A polycarbonate, branched with isatin-bisphenol of
Example 1 and 0.7% by weight of dipotassium
eicosane-disulphonate.
EXAMPLE 7
A 15% strength solution in methylene chloride was prepared of a
polycarbonate of bisphenol A which was prepared by the interfacial
process and which had a relative viscosity of 1.70 (measured as a
0.5% strength solution in methylene chloride). 0.6% of potassium
perfluorobutanesulphonate, relative to the polycarbonate, was added
in the form of an alcoholic solution to this solution. After
degassing, the solution was cast to give a film 0.1 mm thick in a
drum casting machine.
COMPARISON EXAMPLE C to EXAMPLE 7
The polycarbonate from Example 7 was cast to give films 0.1 mm
thick by the process described in Example 7 (a) without the
addition and (b) after the addition of 0.5% by weight of potassium
acetate.
The table which follows contains the measured values.
__________________________________________________________________________
Comparison Comparison Comparison Example 1 2 3 4 Example A 5
Example B 6 7 Example
__________________________________________________________________________
C Metal sulphonate type.sup.(1) A A B C -- KAc A -- K.sub.2
SO.sub.4 D A -- KAc % by weight 0.5 0.2 0.5 0.6 -- 0.5 0.5 -- 0.5
0.7 0.6 -- 0.5 Tetrabromobisphenol -- 4 -- -- -- -- -- -- -- -- --
-- polycarbonate M.sub.n = about 8,000 % by weight Oxygen Index at
0.1 mm 25 26 26 25 21 21 25 21 21 25 26 21 21 thickness (ASTM D
2,863-74) .degree.C. Small burner test at K1/ K1/ K1/ K1/ K3/ K3/
K1/ K3/ K3/ K1/ K1/ K3/ K3/ 0.1 mm thickness F1 F1 F1 F1 F3 F3 F1
F3 F3 F1 F1 F3 F3 (DIN 53,438) UL Subj. 94, VTF 0 0 0 0 >30
>30 0 >30 >30 0 0 >30 >30 sec- sec- sec- sec- sec-
sec- onds onds onds onds onds onds Tensile strength 82 80 85 88 88
82 87 88 83 90 >100 >100 >100 (DIN 53,455) MPa Elongation
at break 95 92 98 91 95 93 >100 >100 >100 90 >100
>100 >100 (DIN 53,455) % Elongation at break (%) 55 56 60 54
22 15 35 10 8 35 >100 >100 50 after 10 seconds storage in
toluene/n-propanol 1:3.5 Dielectric constant 3.2 3.1 3.2 3.2 3.1
3.2 3.2 3.1 3.2 3.2 3.2 2.9 3.0 (20.degree. C./50 Hz) (DIN 53,483)
Dielectric loss factor 12.7 17 15 19 14 19 25 23 24 22 32 30 31
tan. .gamma..10.sup.4 (20.degree. C./50 Hz) (DIN 53,483) Volume
resistivity 2 .multidot. 10.sup.16 10.sup.16 10.sup.16 2 .multidot.
10.sup.16 2 .multidot. 10.sup.16 10.sup.16 10.sup.17 10.sup.17 9
.multidot. 10.sup.16 2 .multidot. 10.sup.16 2 .multidot. 10.sup.16
2 .multidot. 10.sup.16 2 .multidot. 10.sup.16 .OMEGA. . cm (DIN
53,482) Electrolytic corrosion A 1 A 1 A 1 A 1 A 1 AN2 A 1 A 1 AN2
A 1 A 1 A 1 AN2 (DIN 53,489) Stability to heat .degree.C. 153 152
154 154 154 153 154 155 154 153 154 154 153 (VDE 0345 25).sup.2
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.sup.1 Metal sulphonate type: A = potassium
perfluorobutanesulphonate B = potassium perfluoromethanesulphonate
C = potassium perfluorooctanesulphonate D = dipotassium
eicosanedisulphonate KAc = potassium acetate .sup.2 VDE 0345 25
defines the stability of films at tension during thermal
conditions. The influence of increase of temperature on a film
which is under constant mechanical tension, is measured. The
temperature is indicated at which the length of the film has been
elongated for 40% o at which the film has been teared.
Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *